Objective: Case report presentation.

Background: In frontotemporal dementia with parkinsonism (FTDP), several mutations in MAPT gene have been identified, and numerous family cases were reported, since this mutation was first discovered.

Method: Case report.

Results: We present a 48-year-old, Caucasian woman with FTDP linked to the MAPT gene mutation (c.1842T>G (p.Asn614Lys)). Physical examination and neuropsychological assessment revealed a frontotemporal syndrome. Approximately 1 year later she developed a hypokinetic movement disorder and pyramidal signs. Brain MRI revealed mild frontotemporal atrophy. The history includes a pedigree with an autosomal dominant pattern of transmission. A patient’s sibling with similar syndrome, investigated in 2000, had performed cerebral biopsy with neuropathological findings suggesting a tauopathy associated with a chromosome 17 mutation. Nevertheless, genetic analysis was negative, eliminating initially the attempt to diagnose the FTDP linked to mutation in MAPT, therefore other hypotheses were investigated, namely C9ORF72 among others. With the development of new generation sequencing (NGS) the association with MAPT gene was found.

Conclusion: An important pitfall avoidance option can be the frequent reevaluation of previous diagnosis in families, in which the clinical presentation is strongly indicative of particular mutations without positive confirmation results, especially considering the exponential growth in the number of new mutations and the technique optimization. There is an important diversity in early clinical features of FTDP, therefore an early in-depth DNA analysis is necessary for accurate diagnosis. Even though treatment options are limited, pedigree data and early genetic assessments are crucial for genetic counseling and possibly future clinical trials.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/mapt-mutation-frontotemporal-dementia-with-parkinsonism-when-previous-results-can-skew-the-diagnosis/